Help! Coop ventilation in winter questions

Hello!
New to the forum and having a lot of problems trying to figure out the right way to ventilate a coop during the winter. I have a small flock in my coop which has 2 functioning windows, but no vents or fans in it. I live in northern Wisconsin and I understand there is a need to prevent frostbite here, but need to understand what I need to have or install to achieve this. I seem to have been receiving a lot of contrardictory recommendations.
Thank you!!

Hello there, and welcome to Backyard Chickens! You received a great link from RodNTN, though I have to say, you'll always get different opinions on how things should be done, you have to find what works for you! I hope you enjoy BYC as much as I have!

Thanks all for your help! . After reading the article from Rob, I'm thinking some passive ventilation at the top of the coop to get out some of that moist warm air would be good.. maybe a few roof vents added in. Any thoughts on that?